Project Summary/Abstract Neurological and psychiatric disorders, including drug abuse and addiction, exert a devastating personal and economic toll on patients, families, caregivers, and society. This is in part due to our failure in developing effective medications, which in turn is due to the use of drug discovery platforms that are often not relevant to target diseases. The recent development of induced pluripotent stem cells (iPSCs) from humans makes it possible to screen and validate candidate compounds on human neurons, including those from patients, thus potentially increasing the success rate and speeding up the pace of CNS drug development. BrainXell, Inc. has been a pioneer in developing human patient neural cell-based platforms for CNS drug discovery. We are able to produce large quantities of highly enriched, functionally specialized neurons of consistent quality from human iPSCs through our platform technology of directed neural differentiation and expansion of committed progenitors. However, iPSC-derived neurons are immature, comparable to those at the fetal stage, which makes it difficult for presentation of disease phenotypes and for high-throughput screening (HTS) for drug leads intended for those whose brains are fully mature. In our Phase I project, we identified several molecules that accelerate the expression of synaptophysin (SYP) expression specifically in cortical glutamatergic (Glut) neurons or spinal motor neurons (MN), and formulated Glut and MN maturation supplements that yield mature neurons expressing synaptic markers within a week. In this Phase II project, we propose to develop maturation supplements for the other two neuron subtypes, cortical GABAergic neurons and midbrain dopaminergic neurons. The overarching goal of this proposal is to accelerate neuronal maturation while maintaining a highly pure and homogenous population of neurons, which would allow the practical use of mature human neurons in HTS for neuron activity and function. Formulation of an effective cocktail for rapidly generating human mature neurons and determining the optimal conditions for its application will remove the major roadblock in establishing human patient neuron-based HTS for CNS drug discovery.